The present invention provides a connection mechanism adapted to make a releasable connection between a syringe plunger and a drive member of an injector. The drive member is preferably movable in a generally reciprocal linear manner to control movement of the plunger within the syringe. The connection mechanism comprises at least one capture member attached to the plunger. The capture member forms a releasable connection with the drive member upon contact of the drive member during linear forward motion of the drive member when the capture member is rotated relative to the drive member to an engagement position. The capture member is further adapted to disconnect from the drive member upon rotation of the capture member relative to the drive member to a disengagement position.